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Nano-biosensors to boost detection of foodborne pathogens - research

By Rory Harrington, 01-Apr-2011

A nano-based biosensor that could be used for early stage detection of foodborne pathogens such as E.coli and salmonella is under development by scientists in the US.

Researchers at Kansas State University are using carbon nanofibres (CNF) as part of the biosensors to detect the bacteria, an application which could have a huge take up in the state’s huge meat processing sector, they said.

Jun Li, associate professor of chemistry, and doctoral student Lateef Syed, said they chose CNFs because they are able to form an array of tiny electrodes even smaller than bacteria and viruses. When these microbial particles are captured at the electrode surface, an electric signal can be detected.

The associate professor said the technology could be brought to market in around two years.

Work started at NASA

Prior to his arrival at the university in 2007, Li spent seven years at NASA Ames Research Center conducting research into nanotechnology. The current project is an extension of the work he began at the California site.

“The biosensors rely on an array of nanoelectrodes,” he told FoodProductionDaily.com. “We have a unique way of growing CNFs of ~100 nm in diameter vertically from a pre-patterned electrical circuit.”

He added the CNFs and the circuits underneath are encapsulated with silicon dioxide (SiO2) to provide electrical insulation and mechanical anchoring. Excess SiO2 is removed by mechanical polishing and reactive ion etching so only the very end of the CNF tip is exposed.

“This embedded CNF nanoelectrode array chip is then packaged with counter electrodes and reference electrodes in a microfluidic chip through which the sample solution can be passed through”, said Li.

In-line monitoring

The team aims to calibrate the system to detect specific pathogens. The final system should be able to detect 1 bacterium in 100 mL water (the EPA standard) in less than an hour without going through polymerase chain reaction (PCR) or culture.

"A goal is to integrate this technology into a hand-held electronic device for pathogen detection so that we can use this device for in-line monitoring of water quality or food quality at industrial processing sites," said Syed. "We have some preliminary results that indicate this technology is feasible."

Li indicated there was flexibility in the way the technology was applied.

“For applications that do not need to push the detection limit, a simple handheld device can do the work.For applications requiring monitoring water quality in a manufacturing line, the sample collection module can be used which continuously concentrate water sample for automated detection,” he said. “For food processing, industry, other sample collection and preparation modules are needed before detection.”

The project was initially supported Canadian-based company Early Warning Inc., which provided the K-State research team with $240,000 for two years as part of the developmental work. Recently, the US Department of Homeland Security Center of Excellence for Emerging and Zoonotic Animal Diseases, or CEEZAD, have come onboard.

"Kansas is a leading state in meat production and the poultry industry," said Sayed. "Any outbreak of pathogens in these industries causes huge financial losses and a lot of health risks. We want to prevent these outbreaks by detecting pathogens at an early stage."